Welcome to brain Stuff production of I Heart Radio, Hey brain Stuff, Lauren Volga bam here. Every fall, the seasonal flu rears its ugly head. In twenty nineteen, about thirty eight million people in the United States alone got sick
with the flu, and twenty two thousand died. According to these Centers for Disease Control and Prevention or c d C, the best way to protect yourself from getting sick each year is by getting one of that year's formulations of the influenza vaccine, either the flu shot or the nasal spray flu vaccine. But if you're allergic to eggs, you might have been cautioned against it. But why eggs Well, the most common way flu vaccines are made is via
an egg based manufacturing process. Basically, the way these vaccines are made is that first scientists around the world work together to identify which mutations or genetic strains of the flu are likely to have the most impact in the coming year. Then researchers use chicken eggs as a medium in which to grow, or rather replicate, a whole bunch
of those viruses. This actually requires an extra step. We see eggs are an inexpensive and effective medium for virus replication in general, but most strains of the flu that are potentially dangerous to humans aren't that good at growing in eggs, and so researchers develop special strains of the dangerous strains that are called candidate vaccine viruses, or cvvs. Cvvs have a lot in common with the original danger strains, but are also good at replicating inside of chicken eggs.
One way that scientists create cvvs is by injecting eggs with both one of those strains of the flu identified as potentially dangerous and also a strain that's good at growing in eggs. The two strains will sort of mix and match genetically, and the scientists can then select cvvs have both properties. Once you have your CVV, scientists inject them into new chicken eggs and leave them to incubate
for several days. This allows the virus to replicate. Then, the fluid from the eggs containing the viruses is harvested and processed and used to create vaccines. Because this fluid from eggs is used in creating most flu vaccines, most types of flu vaccines do contain a small amount of egg protein, which may trigger an allergic response in people. With egg allergies, So should people with egg allergies avoid getting annual flu shots. Not necessarily. Here's how egg allergies
work in brief. When someone with an egg allergy gets egg in their system, their immune system goes into attack mode against the proteins in the white spand or the yolks of the egg. Their immune system sends out a barrage of compounds to defend itself. This battle between allergens and your bodies. Defend compounds, most notably, histamine, triggers allergy symptoms, which can range from a mild rash to life threatening anaphylaxis. This doesn't mean that people with egg allergies shouldn't get
flu shots. The CDC now recommends that people with the history of egg allergies, regardless of the severity, are okay to receive any licensed, recommended, and age appropriate influenza vaccine. This decision is based on studies of both the nasal spray vaccine and the flu shot in people with and without egg allergies. The rate of anaphylaxis after all vaccines is one point three one per one million doses. Given that's super low, the CDC does recommend the people with
a history of severe allergic reactions to eggs. That is, anyone who has gotten anything more serious than hives from eggs. Be vaccinated in a medical setting such as a hospital, clinic, health department, or doctor's office by a healthcare provider trained to recognize and manage an allergic response. Just as a precaution, they'll keep an eye on you for about half an hour just to make sure you don't have a negative reaction.
But the risk of a bad reaction to a flu vaccine due to an egg allergy is so low, and the benefits of having the vaccine and thus probably avoiding getting sick or passing the disease onto people around you are so high that experts recommend it anyway. Flu vaccines made via an entirely different, non egg related process are much more rare, but they do exist. If you're interested in getting one of these, check with a healthcare provider
for potential availability. Today's episode is based on the article can you get a flu shot if you have an egg allergy? On how stuff works dot com, written by Jennifer Walker. Journey brain Stuff is production of by Heart Radio in partnership with how stuff works dot Com and is produced by Tyler Clanang or more podcasts My Heart Radio, visit the heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.